since no one has responded I will give it my thoughts.
allowing the gliders room roaming for two days sounds risky. they are very curious animals, power outlets can be dangerous, and overall seems safer to just let them suffer for two days in a cage. IF they get lots of time outside of cage with you at home, then two days inside cage shouldn't that bad for them and if they have wheel they will get in some exercise.
critterlove.com offers two items.
1. freeze dried items - should be NO EXTRA sugar.
2. happy glider cereal.
these two items should not spoil in two days.
I would probably leave out HPW for the first night (friday night, if I had to do this)
I would consider a nice glider carry bag for the train rides, so you could take them if you want to. 2.5 hours is not to long, our gliders sleep with the TV on, kids being noisy, dogs barking if someone knocks on the door, and me coming home from work and waking them for a minute to say hello. If the crowded train is a danger to their safety I would then maybe not take them.